JPH107707A - Photocuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for photocuring a photocurable material by irradiation with near-infrared rays, wherein the feature of infrared curing can be exhibited without deactivating surface free radicals by supplying an aqueous solution of a water-soluble organic polymer to that surface of the material which comes into contact with air. SOLUTION: This method comprises applying an aqueous solution of a film- forming water-soluble polymer to that surface of aphotocurable material which comes into contact with water and irradiating the material with light in the visible to near-infrared region. This method can alleviate the problem that near-infrared rays generate few free radicals and the curing of the surface cannot be performed due to the deactivation of surface free radicals by oxygen though the rays can reach depths even when the material is one containing a pigment and a filler. The water-soluble organic polymer used is polyvinyl alcohol, polyethylene oxide, carboxymethyl cellulose, starch or the like. The photocurable material used is one containing an ethylenically unsaturated compound, a near-infrared to visible ray radical polymerization initiator, and a filler such as a pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of inhibiting radical polymerization by oxygen on the surface of a photocurable material having excellent curability in the thickness direction even if it contains a coloring pigment, a coloring dye, an extender, a fiber reinforcing material and the like. By coating an aqueous solution of a water-soluble organic polymer capable of forming a film on the surface of the material, it blocks oxygen and improves the curability of the surface, and can easily remove the film after photocuring. Related to curing method.

[0002]

2. Description of the Related Art Conventionally, photopolymerization has been used in a variety of applications such as curing and printing of paints, resin letterpress, for producing printed circuit boards, resists or photomasks, for producing black and white or color transfer or coloring sheets or coloring sheets. In recent years, in particular, from the viewpoint of global environmental issues, energy saving, labor saving in response to rising labor costs, attention has been paid to the possibility of polymerizing at room temperature, which is a feature of photopolymerization, quick drying, the possibility of solventlessness, etc. It is being actively developed.

[0003] The current mainstream of the photo-curing method is ultraviolet light curing using light having a wavelength of 400 nm or less. In recent years, curing using light having a wavelength longer than ultraviolet light, such as near-infrared light, has been studied. (See, for example, JP-A-3-111402 and
-261406). The wavelength of near-infrared light is 740 nm or more, and the wavelength used for curing is larger than that of ultraviolet light, so that the material has good transparency in the depth direction, is thick and has extenders, coloring pigments, coloring dyes, It has an excellent property that it can be photocured even if it contains a fiber reinforcement or the like.

[0004] However, the near-infrared radical polymerization initiators described in JP-A-3-111402 and JP-A-4-261406 have the disadvantage that the amount of generated radicals is small, so that most of the radicals on the material surface are A phenomenon occurs in which the surface is not cured at all due to deactivation by oxygen in the air.
The inhibition of curing by oxygen on the material surface has been a serious problem in ultraviolet light curing, but it has been solved by increasing the solubility of the ultraviolet light radical polymerization initiator to increase the concentration of the initiator. However, this method is difficult because the near infrared radical polymerization initiator described in JP-A-3-111402 has low solubility.

Further, in order to reduce the inhibition of curing by oxygen, addition of amine ("UV curing technology" edited by Technical Information Association)
1991), the addition of triphenylphosphine (JM
acromol, Sci. Chem. , Vol. A25
143 1988). However, these methods have a small effect of reducing the influence of oxygen, and it is impossible to sufficiently enhance the material surface curability with a near-infrared radical polymerization initiator described in JP-A-3-111402. In order to improve the curability of the radical polymerizable resin in the air, a method of adding a wax and a method of using an allyl resin have been put to practical use (“Polyester Resin Handbook”, Eiichiro Takiyama, pp. 745-754).
1988). However, the addition of wax has the disadvantage that the wax bleeds on the surface of the material after photocuring and reduces the adhesion to the top coat, and the use of an allyl-based resin results in poor curability inside the material due to its poor polymerizability. There is a disadvantage that it decreases.

A method of covering the surface of a photocurable material with a film and curing after blocking oxygen is generally known. However, this method is applied to a method having a complicated shape, a method having a curved surface, and the like. Has drawbacks that are difficult to apply.

To remedy this drawback, there has been proposed a method in which a liquid organic polymer or an aqueous solution of an organic polymer is applied to a preform before curing to block oxygen (for example, Japanese Patent Application Laid-Open No. 58-1983). 201628, JP-B-63-3708
No. 2, JP-A-60-10050). However, in these methods, ultraviolet light or visible light is substantially 500
It is an application to a radical polymerization method using a wavelength of nm or less, and since the wavelength of light used for curing is short, the light transmittance in the thickness direction of a composition containing a filler or the like is low, and the curability inside the composition is low. Is not enough.

[0008]

DISCLOSURE OF THE INVENTION The present invention has excellent curability in the thickness direction even if it contains a coloring pigment, coloring dye, extender pigment, or fiber reinforcing material, and inhibits radical polymerization by oxygen on the surface of the material. An object of the present invention is to provide a method of curing a photocurable material that can be completely eliminated.

[0009]

Means for Solving the Problems In order to solve this problem, the present inventors have developed a photopolymerization system comprising a compound having an ethylenically unsaturated bond, a near-infrared light radical polymerization initiator, and a visible light radical polymerization initiator. As a result of diligent study of the method of curing the surface of the curable material, by applying a solution of a water-soluble organic polymer capable of forming a film on the surface of the photocurable material and blocking oxygen in the air, and then irradiating light, The present inventors have found a photocuring method capable of significantly improving the surface curing of a photocurable material, and have completed the present invention. Hereinafter, the present invention will be described in detail.

In the photo-curing method, a photo-curable material is applied to a substrate or preformed, and then an aqueous solution of a water-soluble organic polymer having a film-forming ability is applied to a portion that comes into contact with air to form a photo-curable material. Then, oxygen in the air is completely shut off, and then light is cured by irradiating light in the visible to near infrared region. By applying in a liquid state, there is an advantage that a material having a curved surface or a complicated shape can be applied. The applied aqueous solution of a water-soluble organic polymer forms a film by evaporating water due to heat generated from a light source during photocuring or polymerization heat generated during curing. The formed film can be easily removed by peeling or washing with water after curing, or by directly polishing with abrasive paper or the like.

Examples of the water-soluble organic polymer capable of forming a film for coating the photocurable material used in the present invention include a chemically synthesized water-soluble organic polymer and a natural water-soluble organic polymer. it can. Specifically, as the chemically synthesized water-soluble organic polymer, polyvinyl alcohol, polyethylene oxide, homopolymers and copolymers of polyvinyl acetamide, polyvinyl pyrrolidone, and the like,
Examples of the natural water-soluble organic polymer include gelatin, pullulan, carboxymethylcellulose, starch and derivatives thereof.

A film composed of these water-soluble organic polymers has an appropriate strength and a high shape-retaining ability and is suitable as a coating material at the time of photocuring. If the aqueous solution of the water-soluble organic polymer is too high in viscosity, the coating workability deteriorates, and if it is too low, it flows and the coating layer at the time of coating becomes thin and the oxygen barrier ability is reduced. 5
0 to 2000 cp, preferably 100 to 1000 cp
s.

The light source used in the photocuring method may be any light source that generates near-infrared light from visible light, and specific examples thereof include sunlight, a halogen lamp, a metal halide lamp, and a xenon lamp.

The photocurable material used in the photocuring method of the present invention comprises (A) a compound having an ethylenically unsaturated bond, (B) a near-infrared radical polymerization initiator, (C) a visible light radical polymerization initiator, and D) It is composed of at least one kind of filler selected from color pigments, color dyes, extenders, and fiber reinforcing materials.

The compound having an ethylenically unsaturated group used in the present invention may be any compound as long as it has at least one radically polymerizable ethylenically unsaturated bond in the molecule. , Oligomers and the like. Examples of such radically polymerizable compounds having an ethylenically unsaturated bond include Japanese Patent Application Nos. 7-160030 and 7-2589.
No. 93 can be used.

These ethylenically unsaturated group-containing monomers and oligomers may be used alone or in a mixture of two or more at any ratio. However, the physical properties of the target cured product and the proper working viscosity may be reduced. For this purpose, the weight ratio of the ethylenically unsaturated group-containing monomer to the ethylenically unsaturated group-containing oligomer is from 0: 100 to 90:10, preferably 10: 9.
0 to 80:20.

The photo-radical polymerization initiator used in the present invention includes a near-infrared light radical polymerization initiator and a visible light radical polymerization initiator. Known near-infrared light radical polymerization initiators can be used.
And a combination of a cationic dye capable of absorbing near-infrared light and a quaternary boron salt described in JP-A-4-261406 and the like. As the cationic dye, those described in Table 1 are particularly preferable.

[0018]

[Table 1]

[0019]

[Table 1]

The addition amounts of the cationic dye and the quaternary boron salt are as follows:
The object of the present invention can be achieved by using 0.001 part by weight or more for each 100 parts by weight of the compound having an ethylenically unsaturated group. If it is less than this, polymerization may not be sufficiently performed, and curing may be insufficiently completed, and is preferably in the range of 0.01 to 10 parts by weight. If used in a large amount, the physical properties of the cured product itself deteriorate, which is not preferable.

Known compounds can be used as the visible light radical polymerization initiator. Examples of such compounds are shown in Table 2-1.
Ban and "Ultraviolet Curing System" 84p (Seito Kato 1
989), bisacylphosphine oxide compounds described in Table 2-2 and Japanese Patent Application No. 8-51931, acetophenone compounds described in Table 2-3, Table 2-4. Ban and Japanese Patent Application 8-8
No. 6417, hexaarylbiimidazole compounds, diketone compounds described in Tables 2-5 to 8, and Table 2-9
Thioxanthone compounds described in Nos. 1 to 11; Similarly, “Surface” Vol. 27, p548 (19
89) can also be used.

[0022]

[Table 2]

[0023]

[Table 2]

A P1 type photoradical polymerization initiator such as an acylphosphine oxide compound, a bisacylphosphine compound, or an acetophenone compound alone can decompose and generate radicals by absorbing light alone, A P2 type photoradical polymerization initiator such as a thioxanthone-based compound or a thioxanthone-based compound is used in combination with a hydrogen-donating compound. A hydrogen-donating compound refers to a compound that can donate electrons and protons to an initiator excited by light. Specific examples of hydrogen-donating compounds suitable for diketone compounds and thioxanthone compounds include aliphatic amines such as triethanolamine and methyldiethanolamine, ethyl 4-dimethylaminobenzoate,
Aromatic amines such as isobutyl dimethylaminobenzoate and 4,4′-dimethylaminobenzophenone are exemplified. Similarly, a hexaarylbiimidazole-based compound requires a hydrogen-donating compound, and examples of such a compound include mercapto compounds such as 2-mercaptobenzothiazole and 2-mercaptobenzimidazole;
Examples thereof include tertiary amines such as N-dimethyl-p-toluidine, N, N-dimethylaniline and N-phenylglycine, and 1,3-dicarbonyl compounds such as dimedone. However, the visible light radical polymerization initiator in the present invention is not limited to these examples.

The above-mentioned visible light radical polymerization initiators can be used alone or in combination of two or more in the present invention. The visible light radical polymerization initiator has a role of supplementing the function of the near-infrared light radical polymerization initiator, and is added for the purpose of sufficiently curing the photocurable material. The visible light radical polymerization initiator can achieve its purpose by adding 0.01 parts by weight or more to 100 parts by weight of the compound having an ethylenically unsaturated group, but preferably 0.1 to 10 parts by weight. Department. If the amount is too small, curing may be insufficiently completed. If the amount is too large, deterioration may occur due to the initiator remaining after curing, or the physical properties of the cured product itself may be deteriorated.

A coloring pigment or coloring dye can be added to the photocurable material used in the curing method of the present invention. Examples of coloring pigments include commercially available inorganic and organic color pigments, such as white pigments such as titanium white and zinc white, and black pigments such as carbon black and titanium black. Well-known ones described in Technical Association of Japan (published in 1976) can be used. As the coloring dye, those described in "Dye Handbook" (edited by the Society of Synthetic Organic Chemistry, published in 1970) and the like can be used.

The addition amount of these coloring pigments and coloring dyes is 0 to 10 parts by weight, preferably 0 to 5 parts by weight, based on the compound having an ethylenically unsaturated group. When the amount of the coloring dye or pigment added is more than 10 parts by weight, light transmittance is deteriorated, and curability inside the curable material is deteriorated.

Further, an optional extender can be added to the photocurable material used in the curing method of the present invention.
As the extender referred to herein, powders of silica, silica-alumina, alumina, aluminum hydroxide, quartz, glass, calcium carbonate, kaolin, talc, mica, aluminum sulfate, calcium phosphate, barium sulfate and the like and the surface of those powders Examples include those coated with a polyfunctional (meth) acrylate monomer or a silane coupling agent. Even if two or more different extenders are added,
No problem.

The extender is added in an amount of 0 to 300 parts by weight, preferably 0 to 150 parts by weight, based on 100 parts by weight of the compound having an ethylenically unsaturated bond. 3 extenders
If the amount is more than 00 parts by weight, the impregnating property is reduced and air bubbles are apt to remain, and the fluidity is reduced to lower the workability.

Further, an arbitrary fiber reinforcing material can be added to the photocurable material used in the curing method of the present invention.
The fiber reinforcing material referred to here is an organic and / or inorganic fiber, and known materials such as glass fiber, carbon fiber, aramid fiber, polyethylene terephthalate fiber, and vinylon fiber are used. The shape is used. Of course, these fibers may be used in combination, and the amount used is 0 to 200 parts by weight, preferably 0 to 100 parts by weight, per 100 parts by weight of the compound having an ethylenically unsaturated group.

The present photocuring method can easily improve the surface curability of a photocurable material even if it contains a coloring pigment, a coloring dye, an extender pigment, a fiber reinforcing material and the like. Therefore, the present photocuring method is suitable for curing putty materials, FRP, sealing materials, and the like. Hereinafter, the present invention will be described by way of specific examples. Of course, the present invention is not limited to the embodiments described below.

[0032]

【Example】

(Examples 1 to 13) A rubber mold having a thickness of 3 mm and a hole having a diameter of 20 mm was formed, and this was fixed to a glass plate with a clip. Next, after pouring the following photocurable compositions 1 to 13 into this mold and flattening the composition surface,
An aqueous solution of the water-soluble polymer shown in Table 3 was brush-coated.
Then, a 1.5 kW halogen lamp (GS made by RDS)
(R-15-30L) with an irradiation distance of 30 cm and a light irradiation time of 10 minutes. The curability of the surface was evaluated by peeling off a water-soluble polymer film formed by evaporating water and then examining the surface of the cured product for any tackiness with a finger. The results are shown in Table 3. At the same time ASTM D2979-71
The degree of tack on the surface of the cured product was quantified using the tack measurement method and the inverted probe tack tester (Tack Tester, manufactured by Rigaku Kogyo Co., Ltd.) shown in (1). In this method, a larger value indicates a larger tack. The measurement conditions and results are shown in Table 3.

[0033]

[Table 3]

(Comparative Examples 1 to 13) As comparative examples, the following photocurable compositions 1 to 13 were similarly poured into a mold, and photocured with a halogen lamp without coating an aqueous solution of a water-soluble polymer. The curability of the surface of the cured product was evaluated by quantifying the presence or absence of tack on the surface with a finger and an inverted probe tack tester as in the examples. The results are shown in Table 4.

[0035]

[Table 4]

Preparation of Photocurable Composition (Composition 1) Vinyl ester resin Lipoxy SP-150
9 (Showa Kobunshi), 25 parts by weight of styrene, and 100 parts by weight of talc were kneaded, and then as a photopolymerization initiator, a near-infrared light absorbing dye shown in Table 1-3 (anion part was n-butyltriethyl) Phenyl borate) 0.10 parts by weight,
Tetra n-butylammonium n-butyltriphenylborate 0.50 parts by weight, compounds in Table 2-4
0.50 parts by weight, 2-mercaptobenzothiazole
0.50 part by weight was further added to obtain Composition 1.

(Composition 2) After kneading 75 parts by weight of a vinyl ester resin, lipoxy SP-1529X (Showa Kobunshi), 25 parts by weight of styrene, and 100 parts by weight of talc, as a photopolymerization initiator, 0.10 parts by weight of a near-infrared light absorbing dye (anion part is p-toluenesulfonic acid), 0.50 parts by weight of tetra-n-butylammonium n-butyltri (2-tolyl) borate, 1700 of Irgacure [Table 2-2] No. compound and 2-hydroxy-
1: 3 of 2-methyl-1-phenylpropan-1-one
CIBAGEIGY] was added to obtain a composition 2.

(Composition 3) Vinyl ester resin RF-3
13 (Showa Kobunshi), 30 parts by weight of styrene, 30 parts by weight of calcium carbonate Whiten 306H (Shiraishi Kogyo), and then kneaded.
No.-5 near infrared light absorbing dye (anion part: tetraphenylborate) 0.10 part by weight, tetra n-butylammonium n-butyltri (4-fluorophenyl) borate 0.50 part by weight, Table 2-4 Compound 0.50
Parts by weight, 2-mercaptobenzimidazole 0.50
The composition 3 was added by weight.

(Composition 4) 100 parts by weight of an unsaturated polyester resin Rigolac 2141 (Showa Kobunshi) and 100 parts by weight of aluminum hydroxide NB-1 (Showa Denko) were kneaded, and then kneaded as shown in Table 1 as a photopolymerization initiator. No. 1 near-infrared light absorbing dye (the anion part is tetraphenylborate)
0.10 parts by weight, tetra n-butylammonium n-
Butyl tri (4-fluoro-2-methylphenyl) borate 0.50 parts by weight, compound 0.50 in Table 2-4
Parts by weight, N, N-dimethyl-p-toluidine 0.50
By weight, the composition was further added to obtain composition 4.

(Composition 5) After kneading 100 parts by weight of an unsaturated polyester resin Yupika 6424 (Yupika) and 100 parts by weight of aluminum hydroxide H-32M (Showa Denko), Table 1-4 was used as a photopolymerization initiator. Near-infrared light absorbing dye (anion part is tetraanisyl borate)
10 parts by weight, 0.50 part by weight of tetra-n-butylammonium n-butyltriphenylborate and 1.0 part by weight of Irgacure 1700 were further added, and the composition 5
And

(Composition 6) 75 parts by weight of vinyl ester resin lipoxy SP-1509, 25 parts by weight of isobornyl acrylate, 30 parts by weight of milled fiber (crushed glass fiber, NEC Corporation), and then kneaded, followed by photopolymerization As the initiator, the near-infrared light absorbing dyes listed in Tables 1-3.
10 parts by weight (anion part is n-butyltriphenyl borate), tetra n-butylammonium n-butyltri (4-t-butylphenyl) borate 0.50 parts by weight, compound of Table 2-10 No. 0.50 parts by weight Isoamyl p-dimethylaminobenzoate (Nippon Kayaku) 0.50
By weight, a composition 6 was further added.

(Composition 7) 75 parts by weight of vinyl ester resin lipoxy SP-1509, 25 parts by weight of styrene,
After kneading 30 parts by weight of a chopped strand mat (2 inches long) of glass fiber, 0.10 parts by weight of a near-infrared light absorbing dye of Table 1-3 as a photopolymerization initiator (anion part is n-butyl tri- Phenyl borate), tetra n
-Butylammonium n-butyltri (4-tolyl)
0.50 parts by weight of borate, Irgacure 1700
1.0 part by weight was further added to obtain Composition 7.

(Composition 8) After kneading 75 parts by weight of vinyl ester resin lipoxy SP-1519, 25 parts by weight of 9EG-A (Kyoeisha Chemical ether acrylate), and 50 parts by weight of silica cristobalite XPF-10 (Tokai Kogyo), As a photopolymerization initiator, near infrared light absorbing dyes listed in Tables 1-4, 0.10 parts by weight (anion part is tetraanisyl borate), tetra n-butyl ammonium n-
0.50 parts by weight of butyl tri (4-tolyl) borate, 0.50 parts by weight of the compound shown in Table 2-5, and 0.50 parts by weight of triethanolamine were further added to obtain composition 8.

(Composition 9) 70 parts by weight of polyester acrylate Aronix M-6400, 9EG-A
(Kyoeisha Chemical ether acrylate) 30 parts by weight,
After kneading 50 parts by weight of alumina UA-5105 (Showa Denko), 0.10 parts by weight of a near-infrared light-absorbing dye shown in Table 1-4 as a photopolymerization initiator (anion part is tetraanisyl borate); n-butyl ammonium n
-Butyl tri (4-t-butylphenyl) borate
0.50 part by weight of the compound of Table 2-10, 0.50 part by weight of isoamyl p-dimethylaminobenzoate (Nippon Kayaku) was further added to obtain composition 9.

(Composition 10) After kneading 75 parts by weight of vinyl ester resin lipoxy SP-1529X, 25 parts by weight of styrene, and 1 part by weight of titanium oxide CR-90 (Ishihara Sangyo), the mixture was used as a photopolymerization initiator in Table 1 No. 5 near infrared light absorbing dye 0.10 parts by weight (anion part is tetraanisyl borate), tetra n-butyl ammonium n
-Butyl triphenyl borate 0.50 parts by weight, Table 2
No.-4 compound 0.50 parts by weight and 2-mercaptobenzothiazole 0.50 parts by weight were further added to obtain composition 10.

(Composition 11) After kneading 100 parts by weight of an unsaturated polyester resin Rigolac G-200GMA and 1 part by weight of an oxide yellow, the near-infrared light-absorbing dye shown in Table 1-1 as a photopolymerization initiator was added. 10 parts by weight (anion part is tetraanisyl borate), 0.50 parts by weight of tetra-n-butylammonium n-butyltri (2-tolyl) borate, and 1.0 part by weight of Irgacure 1700 were further added, and the composition 11 and did.

(Composition 12) 90 parts by weight of vinyl ester resin lipoxy SP-1529X, 10 parts by weight of styrene, VALIOSOL RED 330 as a coloring dye
After adding and mixing 1.0 part by weight of 4-T (Orient Chemical Industries), 0.10 part by weight of a near-infrared light absorbing dye of Table 1-3 as a photopolymerization initiator (anion part is n-butyltriphenyl) Borate), tetra-n-butylammonium
0.50 part by weight of n-butyltriphenylborate, 0.50 part by weight of the compound shown in Table 2-4, and 0.50 part by weight of N-phenylglycine were further added to obtain composition 12.

(Composition 13) 90 parts by weight of vinyl ester resin lipoxy SP-1509, 10 parts by weight of styrene, and VALISOL ORANGE as a coloring dye
After adding and mixing 0.5 part by weight of 3209-T (Orient Chemical Industries), 0.10 part by weight of a near-infrared light absorbing dye of Table 1-4 as a photopolymerization initiator (anion part is n-butyltrianisyl) Borate), tetra n-butyl ammonium n-butyl tri (2-tolyl) borate 0.5
0 part by weight and 1.0 part by weight of Irgacure 1700 were added to obtain composition 13.

[0049]

According to the photo-curing method of the present invention, surface curing can be performed without any problem even for a near-infrared light-curable material having a remarkable oxygen inhibition. Further, since the film of the water-soluble organic polymer can be easily removed after photocuring, this is a highly practical method for reducing oxygen inhibition. Therefore, the photo-curing method is suitable for curing a small-area coated material or a relatively small preform such as a putty material, an FRP, a sealing material, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C09D 201/00 PDC C09D 201/00 PDC (72) Inventor Shuichi Sugita 1 Onodai, Midori-ku, Midori-ku, Chiba-shi, Chiba Chome 1-1 Showa Denko Co., Ltd. Research Laboratory

Claims (3)

[Claims] 1. A method comprising applying an aqueous solution of a water-soluble organic polymer capable of forming a film to a portion of a photocurable material which comes into contact with air, and then irradiating light having a wavelength in a range from visible light to near-infrared light. Light curing method. 2. The water-soluble organic polymer capable of forming a film is selected from polyvinyl alcohol, polyethylene oxide, a (co) polymer of N-vinylacetamide, polyvinylpyrrolidone, carboxymethylcellulose, pullulan, starch and derivatives thereof, or gelatin. At least one compound, whose aqueous solution has a viscosity of 50
2. The photo-curing method according to claim 1, wherein the curing speed is 2,000 cps. 3. A photocurable material comprising: (A) a compound having an ethylenically unsaturated bond; (B) a near-infrared light radical polymerization initiator; (C) a visible light radical polymerization initiator; and (D) a coloring pigment, and coloring. The photocuring method according to claim 1, further comprising at least one filler selected from a dye, an extender, and a fiber reinforcing material.